On This Day: December 15th

Castle Cornet in Guernsey, the last stronghold which had supported the King in the Third English Civil War, surrenders.

The town of Ekenäs (Finnish: Tammisaari) is founded by King Gustav Vasa of Sweden.

Stephen III of Moldavia defeats Matthias Corvinus of Hungary, with the latter being injured thrice, at the Battle of Baia.

The Nizari Ismaili garrison of Gerdkuh, Persia surrender after 17 years to the Mongols.

Mongol forces under Hulagu enter and dismantle the Nizari Ismaili (Assassin) stronghold at Alamut Castle (in present-day Iran) as part of their offensive on Islamic southwest Asia.

Sicilian Chancellor Stephen du Perche moves the royal court to Messina to prevent a rebellion.

Jin-Song wars: Military officers conspire against the emperor Wanyan Liang of the Jin dynasty after a military defeat at the Battle of Caishi, and assassinate the emperor at his camp.

Constantine VIII becomes sole emperor of the Byzantine Empire, 63 years after being crowned co-emperor.

Pope Sergius I is elected as a compromise between antipopes Paschal and Theodore.

Vandalic War: Byzantine general Belisarius defeats the Vandals, commanded by King Gelimer, at the Battle of Tricamarum.